Budget Home Porting

[Mystery Bird]

Looking pretty good, have you considered taking some more of the guide boss'?

[Viper]

See 1st sentance in post #30. More work on the guide boss would net little flow maybe 1-2cfm on the intake side gain in flow is 2cfm per 1 Horsepower provided the cam duration and intake system can utilize it. Maybe gain 1/2HP to make a wing shape vs a a beehive or cone. The cone or column is sufficient and doesn't weaken the guide boss area. The area around the guide boss provides more HP for the effort. I researched flow around a column on my 64 chevy c10 292 inline 6cyl siamesed intake ports with a bolt boss in the middle shaped like a column or cylinder. The flow is ----0---- it goes around the object rejoining on the back side to the original flow path. on Street engines
0.125" material should be left on guide bosses for strength and guide retention. I also do not grind into the rocker arm stud boss hole it creates turbulence and lessens flow creates potential for vacume leaks if rocker arm studs not sealed properly and I don't grind down and fill with epoxy worry that it would come loose due to contact with gasoline and zap the engine.

Turn water on medium in sink and place a pencil or pen in center to see flow around a column.

FLOW AROUND A CYLINDER

Airfoils and Airflow [Ch. 3 of See How It Flies]

The following is an article on porting mopar small block heads it shows the areas of porting and the flow bench gains in cfm for porting each area. In column 5 blend guide boss web was worth 7.6cfm at .400" lift and 8.4cfm at .500" lift that is 4.2HP for the effort and the guides are beehived not wing shaped. In column 6 Blending the guide boss roof (area around the guides) results in 12.1cfm gained. On an all out race engine it might make a difference of 1cfm to narrow and wing or remove the guide boss and add bronze guides but for a street engine thinning to a cone shape works and is sufficient. My tools and hands couldn't make a V shape the U shape or o shape works as good and is easier to make the guides into.

I also tried not to widen the ports. Taller narrower ports make better torque due to higher velocity see the following and consider LS1 cathederal ports shape.

360 Engine Head Porting - Mopar Muscle Magazine

Gasket Match( an area of controversy in Porting) 1" into port column 8 was worth 10cfm at .500" lift.

Instead of full porting the most bang for the least effort is Gasket match openings and Deep pocket port(blend valve bowls to seats, shape roof around guides, and guide bosses) for these areas they gained 31cfm in just these areas thats 15.5 horsepower.

Saw your heads and they looked nice in the guide boss area.

[Mystery Bird]

What's your PP measure out at? Looks like you could flatten out the roof some more too.

[Viper]

2.07"h x 1.24"w

[Viper]

Here is a good example of what some mild bowl cleanup, Chamber polishing, and gasket matching heads and intake bowl work on the exhaust and a good valve job with 30 degree backcut on the valves did for LT4 heads.
Intake manifold gasket

GM 12367777 LT4 gasket was used can also be used with ported lt1 heads and manifold.

Gasket port dimensions: 1.245" X 2.285". Center divider width 7/32" top width is 15/64" bottom widthof gasket ~ 1/4"'

LT4 Port Exit Dimensions: A-2.12" x 1.20"


Lt4 intake manifold and lt1 have same port dimension resulting in a mismatch with the larger LT4 Cylinder head Port openings at the top as you can see the LT4 manifold has more meat at the top for porting this mismatch.

http://www.grandsportregistry.com/lt1vslt4_intakes.htm

http://www.camaroz28.com/forums/lt1-...intake-666667/

http://www.digitalcorvettes.com/foru...d.php?t=105770

http://www.grandsportregistry.com/lt1vslt4.htm

Resuts near stock LT4: Rear wheel horse power increased by 22 and peak torque increased 15 ft lbs after the port work. However, torque over 5500 RPM increase about 20 ft/lbs. The engine idled exactly as before with no change in drivability.

Mez's LT4 Head Porting


Smaller LT1 intake gasket for stock or near stock heads

LT1 Port Exit Dimensions: A-2.06", B-1.15"

LT1 part # GM 12524653


LT 1 Fel Pro FPP-1284 Steel Core Laminate/ Printoseal, 2.04 in. x 1.25 in. Port, .060 in. Thick

Felpro 1284 -- 0.075" thick, 2.071" x 1.275" ports (I.D.)
Felpro 95580 -- 0.064" thick, 2.064" x 1.257" ports (I.D.)


Also need to consider head gaskets

Stock replacement for the LT1:
Fel Pro Permatorque Blue Part Number: 9966PT Cost $22ea

Victor/Reinz Part # 5922 Cost $29ea


I think I'll go with the medium Priced Fel Pro 1094's Stainless steel shim no brinelling of aluminum heads. Cost $29 ea


The High performance steel core laminate Fel-Pros are Part # 1074 Cost $49ea

http://forums.corvetteforum.com/c4-t...p-lt4-lt1.html

Fel Pro also makes a MLS gasket similar to Cometics MLS Permatorque Blue 1144-071 $127ea

[Viper]

Information on Porting the Stock Lt1 Intake manifold Clean up the mis-match at the port opening gasket to head transition and polish off the rough casting and disks this can be polished with 220 or 330 Grit cartridge rolls do not try to take off much or you'll grind a hole in the manifold. Just match and polish smooth.

Ported Stock Intake vs. Ported and Epoxy'd Stock Intake...Results - LS1TECH

Flow numbers for DIY intake vs stock, & LE2 head - CamaroZ28.Com Message Board

https://www.google.com/search?q=port...N4yyqAG8z4D4Dg